Digital image data may be acquired at an image input scanner from an image bearing original by illuminating the original and scanning the image thereon with an array of photosensitive elements that produce a response representative of sensed reflected light intensity. In certain situations it is desirable to provide a full width array (FWA), in which the array of photosensitive elements corresponds in length to the width of the original being scanned. Alternatively, a shorter array may be used, with appropriate magnification to accommodate the image to the length of the array. In either case, arrays may be formed from shorter arrays, butted together to form a single large array or staggered in close proximity and electronically stitched together to provide an apparently seamless response.
As the cost of manufacturing arrays with greater resolution, and accordingly larger numbers of photosensitive elements has become more reasonable, it has become desirable to increase resolution (the number of photosensitive elements across the array) and imaging speed. The result has been an dramatic increase in the quantity of image data which must be handled in a relatively short period, and desirably in real time (i.e., data is output from the image processing arrangement at approximately the same rate that it is acquired). One potential solution is to handle image data from portions of the array in separate channels, each channel separately processing image data from a portion of the array and subsequently stitching the channels together at the output to form the image. However, merely abutting the image data would cause a "seamed" appearance in the final output, because the various image processing routines applied to data require information about the neighbor of any particular pixel along the line, or context. Without this context information, an edge pixel in a channel will not be correctly processed.
U.S. Pat. No. 4,602,285 to Beaulier et al. suggests that a video transformation and filtering system provides parallel processing for a high speed real time system may include several filter processors in parallel, allowing target image data points to be processed simultaneously. U.S. Pat. No. 4,439,803 to Michael et al. suggests a distributed video frame store and real time processing system capable of processing in parallel different lines of video information for the video frame stored. The input processor is capable of synthesizing picture points from information related to adjacent picture points. In the Canon CLC-1 digital color copier, it is believed that 5 channels are provided for image data at the array, each channel sensing three colors of image data. Color image data from each channel is separated to form three streams, one for each color. These streams from different channels are merged, and later processed as a whole, in a single channel.